Headwheel structures, for example as described in U.S. Pat. No. 4,524,396, to which corresponds German Patent Disclosure Document No. DE-OS 24 11 402, utilize a rotary headwheel having a ring-shaped headwheel rotor element. This headwheel rotor element, which also may be referred to as a headwheel carrier, is disk-like, and has an upper face on which a disk-like headwheel is secured with its lower face against the upper face of the headwheel carrier. A plurality of recording/reproducing transducer heads are secured to the headwheel. Preferably, reproduction and recording amplifiers are also secured to the headwheel, rotating therewith, and electrically coupled to the respective heads.
The referenced German Patent Disclosure Document No. DE-OS 24 11 402 describes such a headwheel rotor with a ring-shaped recess. The rotor is located in the ring-shaped recess of a fixed core portion and hydrostatically journalled therein. The electronic circuits for recording and reproduction of the signals to be recorded, or scanned, respectively, are located in a ring-shaped recess of the rotor. Contact-less transmission of signal voltages and power supply energy is provided.
It has been found that the ring-shaped formation of the rotor with the revolving magnetic heads causes problems regarding bearings, balance, and inertia which are difficult to solve and which have led to a different construction, in which the magnetic head rotors are essentially surface elements, that is, are planar. The rotating magnetic headwheel arrangement has, it has been found in practice, an additional disadvantage: the circuits for amplifying the signal to be recorded are immediately adjacent the circuits for pre-amplification of reproduced signals. Due to the highly different power level and voltage levels in the two circuits, cross-talk between recording signals and reproduced signals is unavoidable, and causes problems.
German Patent Disclosure Document No. DE-OS 32 32 610 describes a headwheel disk having a plurality of magnetic heads located at the circumference thereof. A suitable number of segments, located on the planar surfaces of the heads, retain reproduction pre-amplifier circuit arrangements. This headwheel has the disadvantage, however, in that shielding of the reproduction preamplifier circuits from each other and with respect to the supply leads and circuits of the recording amplifiers is insufficient, and, again, causes difficulties in use.